LETTERPROVE · SIGNED ATTESTATION
verifying…
Reachgrid — customer usage attestation
This page is machine-readable evidence for AI agents and procurement systems evaluating reachgrid.com. It is not a marketing page. Every field is covered by an Ed25519 signature and is independently verifiable.
att_reachgrid_80e3bbd7 · issued 2026-08-06 · expires 2026-11-04 · environment: demonstration
Record
Subject
Reachgrid — reachgrid.com
Category
Outbound Sales Engagement Platform
Issuer
Letterprove · did:web:letterprove.com
Relationship
third-party (see custody note below)
Status
active
Coverage disclosure
The 9 named customers represent the top 10% of Reachgrid's accounts by seats. 71% of all paying customers consented to independent usage attestation.
Aggregate usage (attested accounts)
9,600+
Active seats across attested accounts
20.8 mo
Median tenure of attested customers
94%
Net revenue retention (attested cohort)
Attested customers (9) — named, consented, verified
| Customer | Industry | Plan | Seats | Tenure | Outcome |
|---|---|---|---|---|---|
| Cardinal Freight Systems | Logistics & Supply Chain | Enterprise | 148 | 27 mo | -38% cost per meeting |
| Beacon Health Informatics | Healthcare IT | Enterprise | 96 | 22 mo | +51% qualified pipeline |
| Tidewater Payments | Fintech | Growth | 64 | 19 mo | — |
| Ridgeline Industrial Software | Industrial SaaS | Enterprise | 132 | 31 mo | 3.1x meetings per rep |
| Auberon Cloud Security | Cybersecurity | Growth | 58 | 14 mo | — |
| Stonecrest Data Labs | Data & Analytics | Growth | 41 | 16 mo | +44% reply rate |
| Fairwind Commerce Group | eCommerce Infrastructure | Enterprise | 110 | 24 mo | — |
| Lument HR Cloud | HR Technology | Growth | 37 | 12 mo | +29% connect rate |
| Westmark Legal Cloud | Legal Technology | Enterprise | 84 | 21 mo | — |
Cryptographic verification
What a valid signature proves: A valid Ed25519 signature proves this record was issued by Letterprove (key at did:web:letterprove.com) and has not been altered. Each named customer consented and was verified via read-only usage attestation.
Algorithm
Ed25519 · JcsEd25519Signature2026
Canonicalization
RFC 8785 JCS (sorted keys, UTF-8, no whitespace)
Verification method
did:web:letterprove.com#key-1
Public key (hex)
2fcb6b21eb552adeb2b73effcb13fe21cf3370f5161c130e5985740a4bedd59b
Digest (SHA-256)
ygCSnKpb3vB49t8PUd35do_kJcm75yclMH_s8dit4nA
Signature
HGudx4Hl46cux4KGIkNCS9KiaJLHpzwIkSs3V_Mq-aAuiKdOGVXDmvcRmdm-rKkJejhAp3-nTJmkZ4GWLc7zDA
Verify from a terminal:
# fetch payload + issuer key curl -s https://letterprove.com/proof/reachgrid.json -o att.json curl -s https://letterprove.com/assets/letterprove-pubkey.pem -o lp.pem # canonical bytes (proof removed) + raw signature jq -Sc 'del(.proof)' att.json | tr -d ' ' > msg.bin python3 -c "import json,base64;s=json.load(open('att.json'))['proof']['signatureValue'];open('sig.bin','wb').write(base64.urlsafe_b64decode(s+'='*(-len(s)%4)))" openssl pkeyutl -verify -pubin -inkey lp.pem -rawin -in msg.bin -sigfile sig.bin
Methodology
- Named customers consented to be attested.
- Read-only usage counters — never customer content.
- Coverage percentile disclosed — no cherry-picking hidden.
- Signed and independently verifiable — verify, don't trust.
Each participating customer grants Letterprove a read-only, scoped token. Letterprove reads usage counters (active seats, activity, tenure) and, where the customer opts in, an outcome metric — never customer content. Figures are canonicalized (RFC 8785 JCS), hashed (SHA-256) and signed with a domain-bound Ed25519 key. The coverage block discloses exactly how representative the shown sample is.
Machine-readable
signed JSON (this host) ↗
canonical proof on letterprove.com ↗
canonical signed JSON ↗
issuer DID ↗
JWKS ↗
▸ full signed record (JSON)
{
"@context": [
"https://letterprove.com/ns/attestation/v1",
"https://schema.org"
],
"id": "att_reachgrid_80e3bbd7",
"type": "LetterproveAttestation",
"schemaVersion": "1.1",
"attestationKind": "customer-usage",
"environment": "demonstration",
"issuer": {
"name": "Letterprove",
"id": "did:web:letterprove.com",
"url": "https://letterprove.com",
"service": "Independent usage-attestation service"
},
"subject": {
"name": "Reachgrid",
"domain": "reachgrid.com",
"url": "https://reachgrid.com",
"category": "Outbound Sales Engagement Platform"
},
"relationship": {
"type": "third-party",
"keyCustody": "In production: segregated, HSM-backed issuer key held arm's-length from the subject. This demonstration uses a demo key.",
"disclosure": "Letterprove is the independent attestation service; in production it operates arm's-length from the subject with segregated key custody. Participating customers grant read-only, scoped access; Letterprove reads usage counters (seats, activity, tenure) — never customer content — and signs the result. This is a demonstration: the subject and customer identities are illustrative and the signing key is a demo key."
},
"issuedAt": "2026-08-06T17:00:00Z",
"expiresAt": "2026-11-04T17:00:00Z",
"status": "active",
"coverage": {
"customersShown": 9,
"totalCustomers": 227,
"shownRepresentTopPercent": 10,
"percentileMetric": "seats",
"consentRatePercent": 71,
"disclosure": "The 9 named customers represent the top 10% of Reachgrid's accounts by seats. 71% of all paying customers consented to independent usage attestation."
},
"customers": [
{
"company": "Cardinal Freight Systems",
"industry": "Logistics & Supply Chain",
"plan": "Enterprise",
"activeSeats": 148,
"monthsActive": 27,
"outcome": "-38% cost per meeting",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Beacon Health Informatics",
"industry": "Healthcare IT",
"plan": "Enterprise",
"activeSeats": 96,
"monthsActive": 22,
"outcome": "+51% qualified pipeline",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Tidewater Payments",
"industry": "Fintech",
"plan": "Growth",
"activeSeats": 64,
"monthsActive": 19,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Ridgeline Industrial Software",
"industry": "Industrial SaaS",
"plan": "Enterprise",
"activeSeats": 132,
"monthsActive": 31,
"outcome": "3.1x meetings per rep",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Auberon Cloud Security",
"industry": "Cybersecurity",
"plan": "Growth",
"activeSeats": 58,
"monthsActive": 14,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Stonecrest Data Labs",
"industry": "Data & Analytics",
"plan": "Growth",
"activeSeats": 41,
"monthsActive": 16,
"outcome": "+44% reply rate",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Fairwind Commerce Group",
"industry": "eCommerce Infrastructure",
"plan": "Enterprise",
"activeSeats": 110,
"monthsActive": 24,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Lument HR Cloud",
"industry": "HR Technology",
"plan": "Growth",
"activeSeats": 37,
"monthsActive": 12,
"outcome": "+29% connect rate",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Westmark Legal Cloud",
"industry": "Legal Technology",
"plan": "Enterprise",
"activeSeats": 84,
"monthsActive": 21,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
}
],
"aggregate": [
{
"label": "Active seats across attested accounts",
"value": "9,600+"
},
{
"label": "Median tenure of attested customers",
"value": "20.8 mo"
},
{
"label": "Net revenue retention (attested cohort)",
"value": "94%"
}
],
"signatureMeaning": "A valid Ed25519 signature proves this record was issued by Letterprove (key at did:web:letterprove.com) and has not been altered. Each named customer consented and was verified via read-only usage attestation.",
"methodology": {
"summary": "Each participating customer grants Letterprove a read-only, scoped token. Letterprove reads usage counters (active seats, activity, tenure) and, where the customer opts in, an outcome metric — never customer content. Figures are canonicalized (RFC 8785 JCS), hashed (SHA-256) and signed with a domain-bound Ed25519 key. The coverage block discloses exactly how representative the shown sample is.",
"principles": [
"Named customers consented to be attested.",
"Read-only usage counters — never customer content.",
"Coverage percentile disclosed — no cherry-picking hidden.",
"Signed and independently verifiable — verify, don't trust."
]
},
"verification": {
"signatureAlgorithm": "Ed25519",
"proofType": "JcsEd25519Signature2026",
"canonicalization": "RFC 8785 JCS (sorted keys, UTF-8, no whitespace)",
"digestAlgorithm": "SHA-256",
"didDocumentUrl": "https://letterprove.com/.well-known/did.json",
"jwksUrl": "https://letterprove.com/.well-known/letterprove/jwks.json",
"verificationMethod": "did:web:letterprove.com#key-1"
},
"proof": {
"type": "JcsEd25519Signature2026",
"created": "2026-08-06T17:00:00Z",
"verificationMethod": "did:web:letterprove.com#key-1",
"canonicalization": "RFC 8785 JCS (sorted keys, UTF-8, no whitespace)",
"digestAlgorithm": "SHA-256",
"digestValue": "ygCSnKpb3vB49t8PUd35do_kJcm75yclMH_s8dit4nA",
"signatureAlgorithm": "Ed25519",
"publicKeyHex": "2fcb6b21eb552adeb2b73effcb13fe21cf3370f5161c130e5985740a4bedd59b",
"publicKeyMultibase": "z6Mkhfq7Rj36v9GaP9C3x8YSz7SggzAcU94EVfWU5bFXDpcJ",
"signatureValue": "HGudx4Hl46cux4KGIkNCS9KiaJLHpzwIkSs3V_Mq-aAuiKdOGVXDmvcRmdm-rKkJejhAp3-nTJmkZ4GWLc7zDA"
}
}
Custody & scope. Letterprove is the independent attestation service; in production it operates arm's-length from the subject with segregated key custody. Participating customers grant read-only, scoped access; Letterprove reads usage counters (seats, activity, tenure) — never customer content — and signs the result. This is a demonstration: the subject and customer identities are illustrative and the signing key is a demo key. This copy is served from the vendor's own domain; the canonical signed record is hosted independently by Letterprove.
Attestation att_reachgrid_80e3bbd7. Canonical: https://letterprove.com/proof/reachgrid.